The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device including alignment films formed by so-called light alignment.
The liquid crystal display device is configured such that an electric field is applied to liquid crystal interposed between respective substrates arranged to face each other in an opposed manner to drive liquid crystal molecules corresponding to intensity of the electric field. Due to such behavior of the liquid crystal molecules, a quantity of light corresponding to the behavior of the liquid crystal molecules is allowed to pass through the liquid crystal.
Further, for aligning the liquid crystal molecules in the fixed direction (initial alignment direction) when the electric field is not applied to the liquid crystal, an alignment film is formed on surfaces of the respective substrates which are in contact with the liquid crystal.
Further, to visualize the behavior of the initially aligned liquid crystal molecules generated corresponding to a quantity of electric field applied to the liquid crystal molecules as a quantity of light passing through the liquid crystal, a polarizer is formed on surfaces of the respective substrates on sides opposite to the liquid crystal.
In the liquid crystal display device having such a constitution, recently, with respect to the above-mentioned alignment film, there has been known and used an alignment film which is formed by radiating polarized ultraviolet rays or the like to a polymer film thus imparting an alignment function to the polymer film without applying a rubbing treatment to the polymer film. That is, an alignment film formed by so-called light alignment has been used recently.
With respect to the liquid crystal display device, for example, there has been known a liquid crystal display device which forms a pixel electrode using a comb-teeth-shaped electrode having a large number of electrodes arranged in parallel to each other. On the other hand, as the liquid crystal display device, there has been known a liquid crystal display device having the stepped structure on a surface thereof which faces liquid crystal. In applying a rubbing treatment to an alignment film which is formed to cover the stepped structure, there exists a drawback that the uniform alignment treatment cannot be applied to the alignment film.
In this respect, the liquid crystal display device including the alignment film formed by the light alignment can form the alignment film which is not influenced by the stepped structure below the alignment film and hence, such a liquid crystal display device can impart a reliable alignment function to the alignment film.
As described above, the liquid crystal display device which includes an alignment film formed by the light alignment is disclosed in patent document 1 (JP-A-2001-108995) and patent document 2 (JP-A-11-237635), for example.